Procedure for treating cellulose derivative fibres

Abstract

The present invention concerns improving the properties of cellulose carbamate fibres. The wet strength properties in particular can be improved by treating the fibres with alkalis or organic bases, aiming to reduce the number of carbamate groups. The procedure may also be applied in the manufacturing of regenerated cellulose fibres.

We claim: 
     
       1. Method of regulating the wet properties of cellulose carbamate fibres or filaments, which comprises treating such fibres or filaments with a solution of an alkali or of an organic base of a concentration and at a temperature and for a period of time such that the number of carbamate groups in the cellulose carbamate is reduced without adversely affecting the properties of the resulting cellulose carbamate fibres or filaments which thus remain in solid form, thereby increasing wet strength and decreasing wet stretchability of the thus-treated fibres or filaments.   
     
     
       2. The method of claim 1 comprising treating the fibres or filaments with NaOH or KOH solution.   
     
     
       3. The method of claim 2, comprising treating the fibres or filaments with 0.1 to 2% NaOH or KOH solution.   
     
     
       4. The method of claim 2, comprising treating the fibres or filaments with 0.1 to 4% KOH solution.   
     
     
       5. The method of claim 1, comprising treating the fibres or filaments with a tetramethylammonium hydroxide or ethylene diamine solution.   
     
     
       6. The method of claim 5, comprising treating the fibres or filament with 0.1 to 10% tetramethylammonium hydroxide or ethylene diamine solution.   
     
     
       7. The method of claim 1, comprising treating the fibres or filaments at a temperature in the range from room temperature to about 100° C.   
     
     
       8. The method of claim 1, comprising treating the fibres or filaments for a time sufficient to remove substantially all of the carbamate groups, thus obtaining regenerated cellulose fibres or filaments.   
     
     
       9. The method of claim 1, comprising treating the fibres or filaments for a time sufficient to form regenerated cellulose fibres or filaments of less than 10% alkali solubility.   
     
     
       10. In a method for preparing improved cellulose carbamate fibres or filaments comprising the steps of reacting cellulose and urea at elevated temperatures to form cellulose carbamate,   dissolving the thus-formed cellulose carbamate in an alkaline solution to prepare a spinning solution from which cellulose carbamate can be spun, and   spinning the thus-prepared solution through an acid precipitation solution to form fibres or filaments,   the improvement comprising the step of   treating the thus-spun fibres or filaments with a solution of an alkali or an organic base of a concentration and at a temperature and for a period of time such that the number of carbamate groups in the cellulose carbamate is reduced without adversely affecting the properties of the resulting cellulose carbamate fibres or filaments which thus remain in solid form, thereby increasing wet strength and decreasing wet stretchability of the thus-treated fibres or filaments.   
     
     
       11. In the method of claim 10, the improvement comprising the step of treating the thus-spun fibres or filaments with a solution of 0.1 to 4% alkali concentration.   
     
     
       12. In the method of claim 11, the improvement comprising the step of treating the thus-spun fibres or filaments with a solution of 0.1 to 2% alkali concentration.   
     
     
       13. In the method of claim 10, the improvement comprising the step of treating the thus-spun fibres or filaments with a solution of 0.1 to 10% concentration of organic base.   
     
     
       14. In the method of claim 10, the improvement comprising the step of treating the thus-spun fibres or filaments at a temperature in the range from room temperature to about 100° C.   
     
     
       15. In the method of claim 14, the improvement comprising the step of treating the thus-spun fibres or filaments at a temperature of about 100° C. for a period of time of up to about one hour.   
     
     
       16. In the method of claim 10, the improvement comprising the step of treating the thus-spun fibres or filaments for a time sufficient to remove substantially all of the carbamate groups, thus obtaining regenerated cellulose fibres or filaments.   
     
     
       17. In the method of claim 10, the improvement comprising the step of treating the thus-spun fibres or filaments for a time sufficient to form regenerated cellulose fibres or filaments of less than 10% alkali solubility.